A team of international researchers say they have produced the first conclusive evidence linking IQ levels to share ownership.

The University of Chicago's business school surveyed around 160,000 people in Finland in a 19-year period and found that people with higher IQs were more likely to own shares and make better investment decisions than those with lower IQ scores.

The study's co-author, associate professor Juhani Linnainmaa, says the study was based on IQ tests taken by army recruits in Finland, where military service is mandatory.

"If you look at the people who scored the lowest the participation rate is only 9.8 per cent, and if you look at the people who scored the highest the participation rate is as high as 46.5 per cent," Mr Linnainma said.

"Of course IQ scores correlate with many other things, such as education, income and wealth and unemployment ... when we control for all factors the difference in participation rate between the people who scored the highest and the ones who scored the lowest is still 20.5 per cent."

The study found those with high IQ scores tended to hold diversified portfolios and invested in shares that had performed well historically.

"We are not trying to say where the difference is coming from," Mr Linnainma said.

"It could be very possible that maybe people with high IQ scores happen to have better access to information, to even private information, and that could well explain where the difference is coming from."

Mr Linnainmaa says the findings may mean there should be more investment in financial education to level the playing field.